This invention relates to a system for displaying alphanumerical messages by means of a visual display having a row or other plurality of character stations at each of which a character may be produced by the application thereto of a set of binary coded signals, and deals more particularly with such a display system wherein each displayed message may be either one derived entirely from an associated memory or one consisting in part of a message fragment derived from the memory and in part of a message fragment representing a real time condition and derived from a sensor or other device providing a real time output.
The multiple character station display device used in the system of this invention may be any one of a number of different types of such devices wherein each character station includes a number of segments switchable between visible and nonvisible states and arranged so as to permit the generation of any one of a set of alphanumeric characters by making visible different combinations of the segments. Examples of such display devices are Nixie tube displays, light emitting diode (LED) displays, liquid crystal displays (LCD) and vacuum fluorescent displays.
In order to accommodate a reasonably large number of character stations in the display device it is known to multiplex the input signals to the character stations. In such a multiplexing scheme time is divided into repetitive time frames each containing a number of time slots equal to the number of character stations and with each time slot being assigned to a respective one of the display stations. During each time frame sets of binary coded signals representing the characters to be displayed at the various display stations are applied in sequence to a character buss, with the signals intended for a particular character station being applied to the buss during the station's time slot, and the character stations are synchronously enabled during their time slots to receive from the character buss the set of binary coded signals intended for them. In the past, the source of binary coded signals applied to a character buss to create displayed messages has generally been a memory or other message storing means so that the displayed messages have been limited to ones which have somehow been established well in advance of their display.
It is also well known to employ multiple character display devices for displaying the instantaneous values of real time variables such as the time of day, or the pressure, temperature, flow rate, RPM or the like existing at some point in an industrial process, but in such cases the display device is usually permanently associated with a single variable or, if it is capable of being switched to any one of a number of variables, does not include the display of any identifying or informative characters in addition to the ones representing the instantaneous value of the selected variable.
The present invention has as its object the provision of a display system wherein a single multiple character display device may be used to selectively display either messages derived entirely from a memory or messages made up in part of stored message fragments and in part of message fragments derived from real time devices. Thus, for example, the display system may be used in conjunction with an automatic controller for an industrial process and, in accordance with different conditions monitored by the controller, may display complete stored messages advising an operator of the conditions of various aspects of the controlled process, such messages perhaps giving warnings of departures from normal or perhaps giving instructions to the operator for actions to be taken on his part to bring the process back to normal or to otherwise keep it running properly. Additionally, the controller may periodically or at other appropriate times cause the display device to show the instantaneous values of various real time variables existing in the controlled process with each such displayed value having associated with it an informative legend or other supporting multiple character message fragment. In such an application the automatic controller for the involved process makes the selection of messages displayed by the display device; however, the display system of the invention is not limited to such a situation and may be used with various different other kinds of message selecting means.
Other objects and advantages of the invention will be apparent from the following detailed description of the preferred embodiments thereof and from the accompanying drawings.